UEFI

Hey! After working through this book, would the end result be UEFI compatible?
If it is, you should acknowledge that in the BIOS section. Maybe even rename it to "BIOS/UEFI"

[OrdoFlammae]

Unfortunately, I do not know enough about UEFI specifically to be able to tell, but I suspect that without certain modifications it would not be. It would be an interesting project though to figure that out.

For sure! I 100% get that. I don't understand UEFI that well either. Let's keep it open though in case you ever make it work. Anyway, thanks! If anyone else sees this who does know enough about UEFI, please help out.

Oh, one more thing: I'm sorry to inform you, but this book will become a fair bit useless if we don't support this, because the legacy bios support has been dropped by Intel, meaning all old non-UEFI OS's will be dead on new hardware. So, this is very important.

[OrdoFlammae]

Yes, you are correct about keeping up-to-date with hardware. I'm looking into what would need to change in order to work with UEFI. The primary problem with this book is that a good deal of the strategy would need to change, since UEFI has a completely different idea of how to do things. I currently don't know exactly how wide-ranging these changes would be (do I need to eliminate GRUB from the whole process?), and, depending on how far that might go, it could be more worth-while to create a whole new set of tutorials that work from a UEFI standpoint.

Useful resources to look into:
https://wiki.osdev.org/UEFI
https://wiki.osdev.org/UEFI_App_Bare_Bones

Ah, that's too bad. Although, I believe certain versions of grub do support UEFI, so hopefully kernel code won't change too much. If you do a new book, I would love if it kept the same formatting like this one. It seems like this book is fairly minimal, being called "littleosbook", so capturing concepts and the code necessary into digestible, byte-sized pieces would probably be the best. Another similar book which also doesn't support UEFI is here: https://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/os-dev.pdf so maybe you could get some inspiration from that in terms of the way things are explained. I fully support you, and maybe I could help too in the research and writing of the new book if that's the route we take. Thanks a ton!

EDIT: A lot of old BIOS tutorials start with assembly, but it seems like most UEFI tutorials don't. So, I think this could help for teaching people a more bare metal way to help in understanding, since this resource is about actually writing UEFI code in assembly: https://johv.dk/blog/bare-metal-assembly-tutorial I haven't read/worked through it yet, but I'm going to for my own purposes. But, also if you need help with the next edition, hopefully I'll be able to help a little better afterwards.